The invention relates to a tensioning device for a sliding gate provided on the nozzle of a vessel containing molten metal, the sliding gate including a housing, a bottom plate permanently installed therein, a sliding plate adjustably mounted in a housing cover and sealingly and resiliently pressed against the bottom plate by means of clamping units hinged to the housing and crossing under the housing cover.
In a sliding gate of the prior art disclosed in Swiss Patent CH-PS No. 639 301 and of the type described above, the tensioning of the sliding plate against the bottom plate occurs via adjusting screw means which are distributed over the circumferential sides and act on the housing and on the cover and, upon being tightened, produce a surface pressure on the sliding plate. The adjusting screw means each have a screw bolt pivotally suspended on a hinging shaft acting as a clamping unit, a threadless sleeve crossed under the housing cover, a lock nut and cup springs inserted between sleeve and nut. In order to be able to produce the required adjustable surface pressure, these cup springs require a rather elaborate and exact fabrication. In addition, it has been shown in practice that cup springs are sensitive and frequently cause defects. Admittedly, a collar provided on the sleeve must protect the springs against external effects, such as heat and dust accumulation, but this will prevent visual inspection of the condition of the springs.